Bittercress prefers cool, moist soil and is most prolific after early spring rains. Mowing will achieve control over time. Do it frequently enough that you remove the flower heads before they become seed pods. As temperatures warm, the plant will die naturally without having reproduced. That means fewer weeds the following season. This weed usually appears before the recommended timing for Green-Up Weed and Feed but you can apply Lawn Weed Control which has no fertilizer when nighttime temperatures are above 50°.